Lysyl oxidase plays a critical role in the maturation of elastin and collagen of connective tissues by oxidizing peptidyl lysine in these proteins to peptidyl alpha-amino-adipic-gamma-semialdehyde, the reactive precursor to crosslinkages in these proteins. This project proposes to probe the structural and catalytic properties of this enzyme in order to more fully understand the important biological function of this enzyme in normal and pathological states of connective tissue. Using the highly purified protein, the basis of the multiplicity of forms of lysyl oxidase found in connective tissues will be explored by peptide mapping, primary sequence studies, and reactivity with specfic antisera prepared against each enzyme species. The reaction of enzyme with tropoelastin a soluble form of elastin, and the ability of enzyme to oxidize tropoelastin and synthetic peptides resembling tropoelastin will be investigated, assessing the affect of coacervation of these peptides and tropoelastin on their substrate potential. The chemical nature of an organic cofactor of the enzyme with carbonyl reactivity will be studied and its possible role in the mechanism of the enzyme will be investigated. We will further refine the totally synthetic assay for lysyl oxidase we have developed for potential clinical and experimental use and utilize this assay to probe the stereochemistry of the active site and mechanism of inhibition by amines. The cellular site of action of lysyl oxidase will also be investigated.